1. Field of the Invention
This invention relates to cardiac stimulators and has specific reference to an improved apparatus of this character which has a reduced weight and reduced overall dimensions.
2. The Prior Art
Cardiac stimulators comprising a fluid-tight metal case capable of isolating the internal component sections from liquids such as blood or lymph circulating in the body cavity in which the stimulator is grafted are already known. In apparatus of this type a battery that does not release any gas is fitted in the case and consist of a dry battery cell enclosing an anode, a cathode and an electrolyte, one pole of the battery being connected to the metal case of the stimulator so as to earth same. Fitted in the stimulator case is another fluid-tight cell or sub-case containing electronic circuit means capable of generating transmitted either to the patient's heart or to a measuring apparatus serving inter alia the purpose of checking the proper operation of the stimulator. As a rule, the battery is a dry battery having a lithium anode and the electrolyte consisting of a liquid or solid material. The positive terminal of the battery is earthed by connecting same to the metal case. The negative terminal of the battery is connected to the electronic circuit having its earth electrically connected to the stimulator case. This stimulator case consists of titanium, a metal compatible with the liquids contained in the human body. Thus, hitherto known stimulators comprise a sealed chamber enclosing the electronic circuitry and separated from an equally sealed battery cell.
Stimulators according to this known technique are satisfactory in actual service; however, they are relatively heavy on account of their many metal walls and partitions. Now the trend is toward a miniaturization in devices of this kind in order to reduce the patient's discomfort likely to derive therefrom, and also to permit the grafting of devices of this type to very young children.